4-aminopyrazolo [3, 4-a] indene derivatives



United States Patent 3,004,983 4-AlVHNOPYRAZOL0{3,4-a]lNDENE DERIVATIVES Bernard Loev, Broomall, Pa., assignor to Smith Kline & French Laboratories, Philadelphia, Pa., a corporation of Pennsylvania 7 No Drawing. Filed May 16, 1060, Ser. No. 29,147 4 Claims. (Cl. 260-310) when:

R represents alkyl having 1 to 6 carbon atoms inclusive, alkenyl having 2 to 6 carbon atoms inclusive, cycloalkyl having 3 to 6 carbon atoms inclusive, cycloalkenyl having 4 to 6 carbon atoms inclusive, phenyl or substituted phenyl such as aminophenyl, halophenyl, lower alkylphenyl or lower alkoxyphenyl;

R represents hydrogen, lower alkyl or acyl;

R and R represent hydrogen, lower alkyl or acyl; and

R represents hydrogen, halogen, trifluoromethyl, lower alkyl, lower alkoxy, hydroxy, nitro and amino.

Preferred compounds of this invention are represented by the following structural formula:

FORMULA II lit.

when:

R represents alkyl having 1 to 5 carbon atoms inclusive, alkenyl having 2 to 5 carbon atoms inclusive or cycloalkyl having 3 to 6 carbon atoms inclusive;

R and R, represent hydrogen or methyl; and

R represents hydrogen, chloro or trifluoromethyl.

The terms lower alkyl and lower alkoxy are used herein to indicate moieties having not more than 4- carbon atoms, preferably 1 or 2 carbon atoms. The term acyl is used herein to indicate moieties having less than 9 carbon atoms such as benzoyl, benzenesulfonyl, lower alkanoyl, for example acetyl or propionyl, or alkyloxycaramido- 1 ,4-dihydropyrazolo [3 ,4-a] indene.

bonyl, for example carbethoxy, carbomethoxy, or carbamoyl.

This invention also includes acid addition salts of the above defined bases formed with organic and inorganic acids. Pharmaceutically acceptable, nontoxic salts formed with nontoxic organic and inorganic acids are particularly advantageous when the compounds of this invention are to be used as therapeutic agents. Such salts are easily prepared by methods known to the art. The base is reacted with either the calculated amount of organic or inorganic acid in aqueous miscible solvent, such as acetone or ethanol, with isolation of the salt by concentration and cooling or an excess of the acid in aqueous immiscible solvent, such as ethyl ether or chloroform, with the desired salt separating directly. Exemplary of such organic salts are those with maleic, fumaric, benzoic, ascorbic, pamoic, succinic, bismethylenesalicyhc, methane, sulfonic, ethanedisulfonic, acetic, propionic, tartaric, salicylic, citric, gluconic, lactic, malic, mandelic, cinnarnic, citraconic, aspartic, stearic, palmitic, itaconic, glycolic, p-aminobenzoic, glutamic, benzene sulfonic and theophylline acetic acids as well as with the S-halotheophyllines, for example, 8-bromotheophylline. Exemplary of such inorganic salts are those with hydrochloric, hydrobromic, sulfuric, sulfamic, phosphoric and nitric acids. Of course, these salts may also be prepared by the classical method of double decomposition of appropriate salts which is well known to the art.

The 4-amino-l,4-dihydropyrazolo[3,4-a]indenes of this invention are prepared by the following procedure:

According to this procedure a pyrazolo[3,4-a]-inden- 4( 1H) -one is reacted with excess formamide at elevated temperature, conveniently at reflux temperature for about 10 to 60 minutes. Cooling and filtering yields the 4-form- The formamido group is hydrolyzed by heating, conveniently at reflux with a mineral acid such as sulfuric or, preferably, hydrochloric acid for a period of about two to eight hours. The mixture is made basic preferably with an alkali metal hydroxide such as sodium or potassium hydroxide to separate the 4-amino-l,4-dihydropyrazolo[3,4-a]indenes of this invention.

Alkylation of the amino group to prepare further compounds of this invention is accomplished in several ways. Monoalkylation is carried out by reacting the primary amino compound with one molar equivalent of an alkyl halide in an organic solvent such as dimethylformamide, conveniently in the presence of an alkali metal carbonate such as potassium or sodium carbonate. Dialkylation is accomplished by the same procedure using at least two molar equivalents of the alkyl halide.

Alternatively monoalkylation is carried out by reacting the primary amino compound with an appropriate aldehyde or ketone in a lower alcohol solvent and catalytical- Patented Oct. 17, 1951 1y. reducing the resulting Schifi base. with acatalystsuch as palladium-on-charcoal or platinum oxide.

Reduction of the 4-formamido-1,4-dihydropyrazolo- [EA-a] indeneintermediates with bimetallic hydride. 'such as lithium aluminum hydride or sodium aluminium; hy dn'r'de; in. ether: solution. such as ethyl etheror tetrahydrofuran gives the monomethylarnino:compoundsof this: in? vention. The dimethylaminocompounds are; prepared. by" treating either the primary amine: or the.- monometlr ylarnino compound. with a; mixture.- of aqueous formalde hyde and formic acid.

Acylation of the amino group. isacc'omplishedby reacting the primary or secondary amino compound with at leastone molar equivalent of an appropriate acyl halide,

' conveniently inthe presence-of an alkalinietal carbonate.

such as sodium'or potassium carbonate.

The 3-substituted pyrazolo[3,4 a.]inden --4(1H) one starting materials are prepared as described in the copending applications Serial No. 848,927, filed October 2-7, 1959 and Serial No. 851,262, filed November 6, 1959, of which I am an inventor. Briefly these compounds are: prepared from Zacyl-lJ-indandiones, which. are either known to the art or are conveniently prepared by con-- densation ofa methyl ketone with a dimethyl or diethyl; phthalate frequently in an aromaticsolvent such as hen.- mile or toluene with an alkaline condensing agent such. as sodium methoxide, sodium ethoxide, sodium hydride or' sodium hydroxide. These 2-acyl-1,3-indandiones are reacted withsubstantially molar equivalent quantities of hydrazine'at elevated temperature, such' as from about 40? C. to 130 C. for a reaction period of" from about 3U minutes to 24 hours ina solvent in which the reactants are substantially" soluble and with which no chemical" reaction occurs, preferably a lower alcohol such as methanol or ethanol, to give the 3-substituted-pyrazolo- [3,4-a]inden-4(-1H-),-one: intermediates.

When a: compound in WhiCh'Rg of Formula I is lower:

alkyl desired, the 3.-substituted-pyrazolo[3,4-a1inden- 4(1H)-one intermediate is reacted with a basic reagent, preferably an alkali metal or its hydroxide, amide, carbonate or hydride to form the N-metal salt, for instance the preferred sodium, potassium or. lithium derivative at the l-position. This N-metal derivative is then reacted with a reactive alkyl halide to give the l-alkyl intermediates.

Compounds in which R, of Formula I is acyl are prepared by forming an N-alkali metal salt at the 1-position of 4-amino-1,4-dihydropyrazolo[3,4-a1indene and reacting this salt with the appropriate acyl halide.

When 2-acyl-l,3-indandione compounds unsymmetricallyv substituted in the benzene ring are cyclized as described above, varying amounts of the two possibleisomers are obtained. These isomersare separated by fractional crystallization of salts' of the 4 aminopyrazolo- [3,4-a1indenes in a suitable solvent such as a lower alkyl' alcohol-for example ethanol or isopropanol.

It will be'appar'ent'to one skilled'in the art that many variations of this invention can be practical. lowing examples are designed to teach fully the preparation of the compounds of this invention and are not meant to limit thescopeof this invention;

Examplal i i A mixture of 97.0 g of dimethyl phthalate, 36.0. g: of'methyl ethyl ketone, 28.5 g. ofsodiurn methoxide and 300 ml. of toluene is. heated at 100 C. for ten hours. Concentrating, dissolving the residue in water, acidifying-j the. aqueous solution withconcentrated hydrochloricacid and. extracting with ether. gives,v after evaporation. of .the. extract, 2-propionyl-1,3.-indandione.

Hydrazine (3.2 g.) and 20.2 'g. of. 2-propionyl-l,3.- indandione in 400 -ml..of ethanol is heated at reflux for twohours. Dilution with cold water .separates 3-ethylpyrazolo[3,4-a]inden-4(lH)-one. r a

Four grams ofTethylpyrazolo[3,4-a1inden-4(1H)-one 7 formamido-1,4:dihydropyrazolo[3,4-a1indene, prepared.

is suspended in5.0. ml. offormamide andv heated at reflux for 30 minutes. Cooling and filtering gives 3-ethyl-4- formamido-1,4-dihydropyrazolo[3,4-a1indene. After recrystallization from methanol the compound melts at 267 8 C. r

i A mixture of 2.0' g, of 3-ethyl-4formamido-l,4-dihydropyrazolo L3,4-a]indeneand50l ml. of 3:1 hydrochloric acid is refluxed for. five hours; After making basic with sodium hydroxide, the oil which separates and; gradually crystallizes is 4-amino'3 ethyl-l-,4-dihydropyrazolo[3,4- a]indene. 1

This amine is dissolved in anhydrous ethanol and treatedfwith' an' excessv of ethereal hydrogen bromide.

Dilution with ether and filtration gives. the dihydrobromide salt, MB; 245-25 0 C.. 7 Example" 2 A tetrahydrofuran solution of 7.4- g. of 3-ethyl-4- as in Example 1, added to 120g. of lithium aluminum hydride in tetrahydrofuran. The mixture is refluxed for ten hours, diluted with. ether and withwater. The organic. layer is separated, filtered and concentrated to give 3-ethyl-l,4-dihydroA-methylaminopyrazolo[3,4411- indene as the'residue. Treatment of this aminewith excess. etherealv hydrogen chloride. gives 3-ethyl- 1,4-dihydro- 4 methylaminopyrazolo[3,4 a]indene diliydrochloride M.P. 2268 C. 7

Example 3 A mixture of 5.6g. of 3-ethyl-1,4-dihydro-4-methylaminopyrazolo[3,4-a] indene (prepared as in Example 2),

I 6.0 g. of formic acid;andf 40 ml. of methanol is treated The fol- An'ether solution of' the above prepared amine is treated with an" excess of ethereal hydrogen chloride to give-the hydrochloride salt as a hemihydrate.

: Example 4 Amixture1of 970i g; ofdimethyL-phthalate and 43.0 g. of 3-methyl-2-butanone is treated with 28.5 g. of so-- dium methoxide. After adding 300 ml. of toluene the mixture is heated on asteam bath forten hours. Evapcrating the volatiles in vacuo, dissolving the residue in water, acidifying the aqueous solution with concentrated hydrochloric acid and extracting with ether gives, upon graporation of the ether" extracts, 2'-isobutyryl-l,3-indanone.

Hydrazine hydrate (10.0 g.) and 2-isobutyryl-l,3-indandione (43.2 g.) are refluxed for. four hours in 400 ml. of ethanol. The solution; is cooled? and diluted with 1 l. of cold water. The rcsultingsolid is'separated to give 3-isopropylpyrazolo [3,4-a] inden-4'( 1H -one.

A mixture of 2.0 g. of 3.-isopropylpyrazolo-[3,4-a1inden-4(1H)-one and 25 ml. offormamide is refluxed for 30 minutes. Cooling and filtering gives 4-formamido-3- isopropyl-1,4-dihydropyrazolo[3,4-a]indene. This formamido compound isrefluxed with 3:1 hydrochloric acid for five hours. Working up as in Example lgives 4 amino-l,4-dihydro-3'-isopropylpyrazolo[3,4 a]indene.

A mixture of l.5 'gfof 4'-a'mino-l,4-dihydi'o 3 isopropylpyrazolo[3,4-a1ind'ene', 5 ml. offormic acid, 25ml. of formaldehyde and 30 ml. of methanolisrefluxed for 18 hours. Concentrating, dissolving thejresiduein water, washing with ethyl acetate; neutralizing, extracting with ethyl acetate and concentrating the extractsgives 1,4-dihydro-3-isopropyl-4-dimethylamirropyrazolo [3,4 a]indene.

methyl 4-trifiuoromethylphthalate) and 1.1 g. of hydrazine hydrate in 100 ml. of ethanol is refluxed for two hours. The solution is cooled and diluted with cold water. The resulting solid is a mixture of isomers, 3-tbutyl-7-trifluoromethylpyrazolo[3,4-a]inden-4 (1H)-one and 3 t-butyl-6-trifluoromethylpyrazolo[3,4-a1inden-4- 1H -one.

These isomers (2.0 g.) are refluxed with 30 ml. of forniamide for 40 minutes to give, after cooling and filtering, a mixture of 3-t-butyl-4-formamido-7(and 6)-trifiuoromethylpyrazolo[3,4 -a jindene. Refluxing these formamido compounds with 3:1 hydrochloric acid for four hours, then basiiying and removing the aqueous layer gives a mixture of 4-amino-3-t-butyl-1,4-dihydro-7- (and 6) -triflucromethylpyrazolo [3,4-a1indene.

An ethyl acetate solution of the above prepared amine isomers is treated with a molar equivalent of maleic acid to give upon concentration and cooling a mixture of the maleate salts which are fractionally crystallized from ethanol to separate 4-amino-3-t-butyl-1,4-dihydro-7-trifluoromethylpyrazolo [3,4-a1indene maleate and the corresponding 6-trifiuoromethyl isomer.

The separated free bases are obtained by dissolving the maleate salt in water, neutralizing with sodium carbonate, extracting with ether and concentrating the extracts.

A mixture of 1.0 g. of 4-amino-3-t-buty1-1,4-dihydro- 7-triiiuoromethylpyrazolo[3,4-a1indene, 2.0 g. of formic acid, 1.5 g. of formaldehyde and 25 ml. of methanol is refluxed for 20 hours. Working up as in Example 4 gives 3 t-butyl-1,4-dihydro-4-dimethylamino-7-trifiuoromethylpyrazolo [3,4-a1pyrazolo [3,4-a]indene.

Example 6 To a mixture of 97 g. of dimethylpthalate, 150 ml. of ligroin and 70 ml. of toluene is added 28.5 g. of sodium methoxide. A solution of 42 g. of cyclopropyl methyl lzetone in 66 ml. of ligroin and 33 ml. of toluene is added drcpwise While azeotrcpically separating methanol. The mixture is cooled and the solid sodium salt is separated. Dissolring the sodium salt in water, acidifying With concentrated hydrochloric acid and filtering and recrystallizing the solid from aqueous ethanol gives 2-cyclopropylcarbonyl-l,3-indandione, IVLP. l30132 C.

A mixture of 21.4 g. of the indandione, 5.0 g. of hydrazine hydrat and 250 ml. of ethanol is refluxed for 24 hours. Cooling, adding water, filtering and recrystallizing the resulting solid from aqueous ethanol gives 3-cyclopropylpyrazoio[3,4 a]inden 4(1H) one, M.P. 212 219 C.

Eight grams of 3-cyclopropylpyrazolo[3,4-a]inden- 4(iH)-one and 109 ml. of formamide are heated at reflux for 30 minutes. Cooling separates 3-cyclopropy1-4- formamido-LZ dihydro-pyrazolo[3,4 a] indene. Refluxing this formamide with hydrochloric acid for live hours, basit'ying and removing the aqueous layer gives 4-amino- 3-cyclopropyl-1,4-dihydropyrazolo[3,4-a1indenc.

Example 7 A mixture of 3.5 g. of 4-amino-3-cyclopropyl-1, 4-dihydropyrazolo[3,4-a1indene, prepared as in Example 6, and 20 ml. of 10% sodium hydroxide is warmed for three minu es. The resulting sodium salt is treated with no equivalent of ethyl chloroformate in 10 ml. of ethanol, then warmed at 60 C. for one hour. The resulting 4-arnino-1-carbethoxy-3-cyclopropyl-1,4-dihydropyrazolo[3,4-a]-indene, is isolated by extraction with ether and evaporation of the organic layer.

in a similar fashion a mixture of 2.3 g. of the sodium salt repared above and 1.0 g. of methyl chloroiormate in 25 ml. of ethanol is refluxed for minutes. Extraction with ether and evaporation of the extracts gives 4- amino-1-carbomethoxy-3-cyclopropyl 1,4 dihydropyrazolo [3,4-a1indene.

Example 8 A mixture of 2.5 g. of 3-cyclopropylpyrazolo[3,4-a]inden-4( 1H)-one, made as in Example 6, and 75 ml. of 10% aqueous sodium hydroxide is warmed very briefly, then concentrated to a small volume. The sodium salt is isolated by filtration. A mixture of 1.5 g. of this salt and 5.0 g. of methyl iodide in 25 ml. of ethanol is heated at reflux for 5 hours. The volatiles are removed to leave 3-cyclopropy-li-methylpyrazolo [3,4-a] -inden-4( 1H) -one.

A mixture of 2.0 g. of 3-cyclopropyl-1-methylpyrazolo- [3,4-a]inden-4(lH)-one and 30 ml. of formamide is refiuxed for 45 minutes. Cooling and filtering gives 3-cyclopropyl-4-formamido-l,4-dihydro l methylpyrazolo[3,4-a]indene. This formamido is refluxed with 3:1 hydrochloric acid for five hours to give after making the solution basic with sodium hydroxide 4-amino-3-cyclopropyl-1,4-dihydro-l-methylpyrazolo [3,4-a1indene,

Similarly the sodium salt (1.0 g.) prepared above is reacted with 8.0 g. of butyl bromide in ethanol solution to give 1-butyl-3-cyclopropylpyrazolo[3,4-a]inden-4(1H)- one. This ketone is refluxed with 15 ml. of formamide for 20 minutes to give, after cooling and filtering, l-butyl- 3-cyclopropyl-4-formamido-1,4 dihydropyrazolo[3,4-a] indene. Refluxing this formamido compound with 3:1 hydrochloric acid for five hours and neutralizing with sodium hydroxide gives 4-amino-1-butyl-3-cyclopropyl- 1,4-dihydropyrazolo[3,4-aJindene.

Example 9 A solution of 5.1 g. of Z-cyclohexylcarbonyl-l,3- indandione and 0.65 g. of hydrazine in 250 ml. of methanol is refluxed for 14 hours to give 3-cyclohexylpyrazolo- [3 ,4-a] inden-4( 1H) -one.

This ketone (4.0 g.) is refluxed with 50 ml. of formamide for 30 minutes to give upon cooling and filtering 3-cyclohexyl-4-iormamido 1,4 dihydropyrazolo[3,4-a] indene.

A mixture of 1.0 g. of 3-cyclohexyl-4-formamido-1,4- dihydropyrazolo[3,4-a1indene and 30 ml. of 3:1 hydrochloric acid is refluxed for four hours to give after basifying and removing the aqueous solution 4-amino-3-cyclohexyl-l,4-dihydropyrazolo[3,4-alindene.

A solution of 1.0 g. of this free base in ethyl acetate is added to an ethanol solution of mandelic acid. Concentration and cooling gives the mandelate salt.

Example 10 A mixture or" 2.5 g. of 2-(1-cyclopenten-1-yl-carbonyl) -5-methyl-l,3-indandione, prepared by condensing diethyl 4-rnethyl phthalate with l-cyclopenten-l-yl methyl ketone, and 0.5 g. of hydrazine hydrate in 200 ml. of methanol is heated at reflux for 48 hours. The resulting solid is a mixture of 3-(1-cyclopenten-1-yl)-6(and 7)- methylpyrazolo 3,4-a] inden-4( 1H) -one.

Refiuxing this mixture of isomers with 25 ml. of formamide for 30 minutes, then cooling and filtering furnishes 3 (1 cyclopenten-1yl)-4-formamido-1,2-dihydro-6(and 7) -methylpyrazolo[3,4-a] indene.

This mixture of isomers is refluxed with 15 ml. of 3:1 hydrochloric acid for five hours. After basifying, the aqueous layer is removed to leave a mixture of l-amino- 3-( l-cyclopenten-l-yl) -l,2-dihydro-6(and 7)-methylpyrazolo-[3,4-a]indene.

An ethanol solution of the free bases is treated with excess ethereal hydrogen chloride to separate the hydrochloride salts Which are fractionally crystallized from ethanol to give 4-amino-3-(l-cyclopenten-l-yl)-1,2-dihydro-6-methylpyrazolo[3,4-a]indene hydrochloride and its 7-methyl isomer The free bases are obtained by dissolving the salts in water, neutralizing, extracting with ether and evaporating the extracts.

7 Example 11' A mixture of 2.6 g. of 2-(l,3-cyclohexadien-l-yl-carbonyl)--hydroxy-l,3-indandione (prepared by condensing 1,3-cyclohexadien-l-yl methyl ket'one with dimethyl 4-acetoxyphthalate and hydrolyzing the O-acetyl group. with %hydrochloric acid) and 0.5 g. ofi hydrazine hydrate in 150 ml. of ethanol is refluxed for hours to give, after. quenching with cold water, .a mixture of 3-( 1,3- c'yclohexadi'enyl) 6 hydroxypyrazolo[3,4-a1inden-4- QI-HQi-one: and. the corresponding 7-hydroxy compound.

These ketones are refluxed with mlof formamide for 45 minutes After cooling, a mixture of 3-(1,3-cyclohexadienyl) -4-formamidol ,4-dihydro-6 (and 7) -hydroxypyrazOloBA-alindene is filtered ofl.

Refluxing these fo'rmamido compounds with 20 ml. of

3:1 hydrochloric acidfor five hours, then basifying and removing the aqueous layer yields 4-amino-3-(l,3-cyclohexadieuyl -l,4-dihydro-6 (and 7 -hydroxypyrazolo- 3,4- a]indene.

'The isomers are separated by dissolving in acetone, treating with a molar equivalent of citric acid in acetone, concentrating and filtering to give a mixture of the citrate salts and fractionally crystallizing the salts from ethanol.

Example 12 A solution of 3.1 g. or" 2-acetyl-5-iodo-l,3.-indandione (prepared by condensing dimethyl 4-iodophthalate with acetone.) and 0.5 g. of hydrazine hydrate in ethanol is 'heated at reflux for one hour. Quenching the reaction mixture gives a mixture of 6(and 7)-iodo-3-methylpyrazolo] 3 ,4-a] inden-4( 1H) -one.

Refluxingtheabove prepared indenones with 25 ml. of; formamide for minutes yields 4-formamido-L4- dihydro 6 (and 7).-iodo-3 methylpyrazolo[3,4-a]indene.

A mixture of 2.0 g. of 4-formamido-l,4-dil1ydro- 6(ar1d 7 )-iodo-3.-methylpyrazolo[3,4-a]indene and ml. of: 3:1 hydrochloric acidxis refluxed for five hours and Worked-up as in Example ll to give 4-amino-L4-dihydro- 6 (and 7 -iodo-3-methylyprazolo 3 ,4-a] indene.

These isomers are separated by converting the free bases to the citrate salts and fractionally crystallizing these salts from ethanol.

Example 13 A. mixture or" 4.0 g. of 3-n-hexylpyrazolo[3,4-a]inden- 4(lH)-one (prepared by condensing dimethyl phthalate with Z-octanone and reacting the resulting Z-n-heptanoyl- 1,3-indandione with one equivalent of hydrazine) and 50 ml. of formamide is heated at reflux for 30 minutes. Cooling and filtering gives lefOIHlfiIYlldO'3'H'h6XYl'1,4- dihydropyrazolo[3,4-a1indene which is refluxed with 25 m1. of 3:1 hydrochloric acid for five hours. Sodium hydroxide solution is added until the mixture is basic. Removal of the water layer leaves 4-a1nino-3-n-hexyl-l,4- dihydropyrazolo[3,4-alindene. v

A mixture of 2.4 g. of 4-amino-3-n-hcxyl-l,4-dihydropyrazolo[3,4-a]indene, 3.0 got u-butyl bromide 5.0 g. r of potassium carbonate and .60 ml. of dimethylformamide is refluxed for ten hours. The cooled reaction mixture is poured into Water and extracted with toluene. The

'toluene layer is separated and evaporated in vacuo.

A mixture of 3.0 g. of 3-(3-butenyl)pyrazololf3,4-a]

inden-4(l-H)-oue (prepared by condensing dimethyl phthalate With 5-hexen-2-one and reacting the thus formed 2-(4-pentenoyl)-l,3-indandione with one equivalent of hydrazine) and 40 ml. of formamide is refluxed for 30 minutes. Cooling and filtering gives 3-(3-hutenyl)-4-tormamido-1,4-dihydropyrazolo[3,4-alindene.

Refluxing this formamide with 3:1 hydrochloric acid for six hours and Working up as in Exmple 13 gives 4- amino-3-( 3-butenyl) 1,4-dihydropyrazol0 3,4-a] indene;

' Example 15 A mixture of 5.0 g. of 3-vinyl- 5(and 7)-bromopyrazolo[3,4-a]inden-4(lH)-one (prepared by reacting di methyl 4-bromophthalate with 3-butenone and treating the resulting product with one equivalent of hydrazine) and 60 ml. of formamide is heated at reflux for 60 minutes, then cooled and filtered to give 3-allyl-6(and 7 bromoi-formamido-1,4-dihydr0pyrazolo [3,4-a] indene.

Refluxing the above prepared isomers with hydrochloric acid for 30 minutes, oasifying and removing the Water layer gives 3-allyl-4-amino-(6 and 7)-bromo-l-. 4-dihydropyrazolo[3,4-a1indene. V

. These isomers are separated by dissolving in ether, treating with excess tartaric acid, filtering and fractionally crystallizing the tartrate salts from ethanol. The separated tartrate salts are converted to the free bases by dissolving in water, basifying, extracting with ether and evaporating the extracts.

Example 16 A mixture of 6.0 g. of 3-(5-hexenyl)-pyrazolo-[3,4-a1- inden-4(lH)-one (prepared by condensing dimethyl phthalate with S-hexene methyl ketone and treating the resulting 2'(6-heptenoyl)-l,3-indandione with one equivalent of hydrazine) and 75 ml. of icrmamide is heated at reflux for 30 minutes to give, after cooling and filtering, 4 -f ormarnido-3-(5-hexenyl) l,4-dihydropyrazolo[3, 4-alindene. Refluxing this compound with 3:1 hydrochloric acid, basiiying and removing the aqueous layer gives 4-amino-3-(5-hexenyl)-l,4-dihydropyrazolo[3,4-a1- indene.

Example 17 A solution of 5.0 g. of 2-benzoyl-1,S-indandione, M.P. l09-l 10 C., and l g. of hydrazine hydrate in 200 ml. of ethanol is heated at reflux for 24 hours. Quenching gives a solid, 3-phenylpyrazolo{3,4-a]inden-4(lH)-one, M.P. 254-255 C.

A mixture of 3.5 g. of B-phenylpyrazolo[3,4-a1iuden- 4(lH)-one and 40 ml. of formamide is heated at reflux for 30 minutes. Cooling'and filtering gives 4-formamidol,4-dihydro-3-phenylpyrazolo[3,4-a1indene which is refluxed with 25 ml. of 3:1 hydrochloric acid to give 4- amino-1,4-dihydro-3-phenylpyrazolo[3,4-a1indene.

An other solution of the free base is treated with excess ethereal hydrogen chloride to give the dihydrochoride salt.

' 7 Example 18 A mixture of 2.0 g. of 3-p-aminophenylpyrazolo-[3,4- a]inden-4(lH)-one (prepared by condensing dimethyl phthalate with p aminoacetophenone and reacting the resulting indandione with one equivalent of hydrazine) and'25 ml. of formamide is refluxed for 30 minutes. After cooling, 3-p-aminophenyl-4-formamid0-1,4-dihydropyrazolo[3,4-a]indene is filtered off.

Refluxing this formamido compound with 25 ml. of 3:1 hydrochloric acid for five hours, then basifying and removing the aqueous layer gives 4-amino-3-p-aminophenyl-l ,4-dihydropyrazolo [3 ,4-a] indene.

Example 19 A suspension of 0.666 mole 15.3 g.) of sodium in 250 ml. of toluene is heated with stirring until the sodium melts. After cooling to room temperature gradually with stirring, the toluene is removed and replaced by 300 m1.

of dry benzene. The mixture is stirred while 0.69 mole (22.0 g.) of dried methanol is slowly added. After reflux period of six hours, the excess methanol is removed. A mixture of 0.666 mole (129.2 g.) of dimethyl phthalate and 0.666 mole (100.0 g.) of p-methoxyacetophenone is added over a period of 30 minutes. Distillation of the reaction mixture is continued until the evolution of methanol stops. The mixture is cooled to separate a solid which is then removed and slurried in an aqueousconcentrated hydrochloric acid suspension. The resulting solid is recrystallized from tert-butanol to give 2-pmethoxybenzoyl-l,3-indanedione, M.P. l23l24 C.

A mixture of 0.1 mole (28.1 g.) of the indane-dione and 0.1 mole (5.0 g.) of hydrazine hydrate in 500 ml. of methanol is heated at reflux for 16 hours. The solution is cooled and diluted with 2 1. of cold water. The resulting solid is separated to give 3-p-methoxyphenylpyrazolo[3,4-a]inden-4(1H)-one, M.P. 264-265 C.

This ketone (8.0 g.) is refluxed with 100 ml. of formamide for 30 minutes. After cooling and filtering, 4- formamido 1,4-dihydro-3-p-methoxyphenylpyrazolo[3,4- alindene is obtained.

A mixture of 5.0 g. of this formamide is refluxed with 3:1 hydrochloric acid for five hours and worked up to give 4 amino-l,4-dihydro-3-pmethoxyphenylpyrazole[3, 4-a1indene.

Example 20 2-p-chlorobenzoyl 5 nitro-1,3-indandione, prepared by condensing dimethyl-4 nitrophthalate with 4-chloroacetophenone, is refluxed with one equivalent of hydrazine to give a mixture of 3-p-chlorophenyl-6(and 7)-nitropyrazolo 3 ,4-a] inden-4( 1H) -one.

Refiuxing this ketone 5 .0 g.) with 60 ml. of formamide, cooling and filtering gives 3-p-chlorophenyl-4-formamido- 1,4-dihydro-6( and 7) nitropyrazolo[3,4-a] -indene which is refluxed with hydrochloric acid for five hours, basified and isolated from the aqueous layer to give 4-amino-3-pchlorophenyl 1,4-dihydro-6 (and 7)-nitropyrazolo[3,4-a] indene.

These isomers are separated by converting to the citrate, salts and fractionally crystallizing.

A mixture of 2.5 g. of 4-amino-3-p-chlorophenyl-1,4-

dihydro 6 nitropyrazolo[3,4-a]indene in 10 ml. of pyridine and a solution of 3 equivalents of sodium hydrosulfite in 10 m1. of water is refluxed for 30 minutes. The mixture is quenched and extracted to give 4,6-diamino-3- p-chlorophenyl-1,4-dihydropyrazolo [3,4-a] indene.

Example 21 A mixture of 2.0 g. of 3-o-bromophenyl-6(and 7)-ethylpyrazolo[3,4-a]inden 4(1H) one (prepared by condensing dimethyl 4 ethylphthalate with o-bromoacetophenone and refluxing the thus formed 2-o-bromobenzoyl- 5-ethyl-1,3-indandione with one equivalent of hydrazine) and 25 ml. of formamide is refluxed for 30 minutes, then cooled and filtered to give 3-o-bromophenyl-6(and 7)- ethyl 4 formamido-1,4-dihydropyrazolo[3,4-a]indene.

Treating this formamido compound with hydrochloric acid gives a mixture of 3-o-bromophenyl-6-ethyl-4-formamido-1,4 dihydropyrazolo[3,4-a1indene and the corre sponding 7-ethyl isomer.

These isomers are separated by fractional crystallization of the citrate salts from ethanol.

Example 23 A mixture of 5.0 g. of hydrazine hydrate and 21.6 g. of 2-isobutyryl-5-chloro-1,3-indandione, made by condensing 3-methyl-2-butanone with dimethyl 4-chlorophthalate, in 200 ml. of ethanol is refluxed for six hours. Cooling, adding water and filtering gives a mixture of 6(and 7)- chloro-3 -isopropylpyrazolo 3,4-a] -inden-4 1H) -one.

Two grams of 6(and 7)-chlor0-3-isopropylpyrazolo[3,4- a] inden-4(lH)-one is suspended in 30 ml. of formamide. The mixture is refluxed for 30 minutes, then cooled and filtered to give 6(and 7)-chloro-4-formamido-1,4-dihydro- 3-isopropylpyrazolo [3,4-a] indene.

A mixture of 1.5 g. of 6(and 7)-chloro-4-formamido-1, 4-dihydro-3-isopropylpyrazolo[3,4-a] indene and 20 ml. of 3:1 hydrochloric acid is heated at reflux for five hours. Basifying and removing the aqueous layer gives 4-amino- 6( and 7)-chlor0 l,4-dihydro-3-isopropylpyrazolo[3,4-a] indene.

These isomers are separated by treating with a molar equivalent of maleic acid in ethyl acetate, fractionally crystallizing the resulting maleate salts from ethanol, dissolving the separated salts in Water, neutralizing with sodium carbonate, extracting with ether and concentrating the extracts.

Example 24 A mixture of 2.5 g. of 4-amino-6(and 7)-chloro-l,4-dihydro 3 isopropylpyrazolo[3,4-a1indene, prepared as in Example 23, and 20 ml. of 10% sodium hydroxide is warmed for five minutes. The resulting salt is refluxed with one equivalent of benzenesulfonyl chloride in other solution for ten minutes. Extraction with ether and evaporation of the extract gives a mixture of isomers 4-aminol-benzenesulfonyl 6(and 7)-chloro-l,4 dihydro-3-isopropylpyrazolo [3 ,4-a] indene.

Separation of these isomers is accomplished by fractional crystallization of the maleate salts.

Example 25 A mixture of 1.0 g. of 4-arnino-1,4-dihydro-3-isopropylpyrazolo[3,4-a]indene, prepared as in Example 4, is converted to the potassium salt by heating with 5% potassium hydroxide. The resulting salt is heated with 0.8 g. of benzoyl chloride in benzene to give 4-amino-l-benzoyl- 1,4 dihydro 3-isopropylpyrazolo[3,4-a1indene.

Similarly by reacting the potassium salt of 4amino-l,4- dihydro-3 isopropylpyrazolo[3,4-a]indene prepared as above with one equivalent acetyl chloride in ether suspension gives upon extraction with ether and evaporation of the volatiles l-acetyl-4-amino-l,4-dihydro 3-isopropylpyrazolo [3,4-a1indene.

The hydrochloride salt is obtained by reacting an ethanol solution of the free base with excess ethereal hydrogen chloride.

Example 26 The potassium salt of 4-amino-1,4-dihydro-3-isopr0pylpyrazolo[3,4-a]indene (1.2 g.), prepared as in Example 25, in refluxed with 0.5 g. of propionyl chloride in benzene for 30 minutes. Extraction with ether and evaporation of the extracts gives 4-amino-1,4-dihydro-3-isopropyl-1- propionylpyrazolo [3,4-a] indene.

Example 27 A mixture of 3-n-butyl-5-methoxypyrazolo [3,4-a]inden- 4 (1H)-one and the corresponding S-methoxy isomer is prepared by condensing dimethyl 3-methoxyphthalate with Z-hexanone and reacting the resulting 4-methoxy-2-valeryl- 1,3-indandione with one equivalent of hydrazine.

These isomers (8.0 g.) are heated at reflux with ml. of formamide to give, after cooling and filtering, 3-ni 11 butyl- 4 fbrrhamido-lA-dihydro-S (and 8') -methoxypyra'=- zolo.[3,4-a] indene.

A mixture of these formamido isomers is refluxed with 40 ml. of 3:1 hydrochloric acid to give 4-amino-3-n-butyl- 1,4-dihydro (and 8) methoxypyrazolo[3,4-a]indene. These isomers are separated by fractional crystallization of the maleate salts;

Example 28 Amixture of 2.5 g. of 4-amino-3-n-butyl-l,4 dihydro-5- mistlioxypyrazolofi,4-a]indene (prepared as in Example 27), (L8 g. of acetyl chloride, 1.1 g. of sodium carbonate and 2-5 ml; of benzene is refluxed for two hours. Cooling, filtering, washing with Water, extracting with ether and distilling the ether from the extracts gives 4-acetamido- 3n'-butyl-1,4-dihydro-5-methoxypyrazol0-[3,4-a]indene.

Similarly, refluxing 2.5 g. of 4-arnino-3-n-butyl-1,4-dihydro-5-methoxypyrazolo[3,4-a]indene with 1.0 g. of propionyl chloride in benzene in the presence of sodium carbonate gives B-n-butyl-1,4-dihydro-5-methoxy-4-propionamidopyrazclo{3,4-alindene.

Example 2 9' A mixture of 3.0 g. of4 amino-3-t-butyl1,4-dihydro-6- trifiuoromethylpyrazolo{3,4-a1indene (prepared as in Example 5) and 1.4 g. of benzoyl chloride in 5Q ml. of benzene is heated at reflux for four hours. Concentrating,

V basifying with sodium carbonate, extracting with ether and evaporating the extracts gives 4-benzamido-3-t-butyl- 1,4-dihydro-6-trifiuoromethylpyrazo1o[3,4-a]indene.

Example 30 A mixture of 2.1 g. of 4-amino-3-cyclopropyl i,4-dihydropyrazoloB,4-a]indene (prepared as in Example 6), 1.8 g. of benzenesulfonyl chloride and ml. of ether is refluxed for two hours. Evaporation of the mixture, treatment of the residue with excess aqueous sodium carbonate, extraction with ether and evaporation of the extracts gives 4-b'enzenesulfonamido-3-cyclopropyl-1,4-dihydropyrazolo[3,4-a]indene.

Example 31 A mixture of 3.0 g. or 4-amino-3-ethyl-1,4-dihydropyrazolo[3,4-a]indene (prepared as in Example 1), 1.0 g. of

methyl chloroformate and 25 ml. of ether is refluxed for one houn Concentrating, treating with aqueous sodium carbonate, extracting with ether and evaporating the extracts gives 3-ethyla1,4-dihydro-4-carbomethoxyaminopyrazoio[3,4-a]indene.

Similarly treating 4-amino-3-ethyl-1,4-dihydropyrazolo- [3,4.-a]indene Withethyl chloroiormate yields 4-carbemeans acid addition salts, the free base having the formula:

R: Rd

in which R; is am'emberselected from the group consisting of alkyl of from 1 to 6 carbon atoms inclusive, a1- kenyl of from 2 to 6 carbon atoms inclusive, cycloalkyl of from 3 to 6 carbon atoms inclusive, cycloalkenyl of from 4 to 6 carbon atoms inclusive, phenyl, aminophenyl, halophenyl, lower alkylphenyl and lower alkoxyphenyl; R R and R, are members selected from the group consisting of hydrogen, lower alkyl, benzoyl, benzenesulfonyl formyl, acetyl; propionyl, carbethoxy, carbomethoxy, and carbarnoyl; and R is a member selected from the group consisting of hydrogen, halogen, trifluororneths yl, lower alkyl, lower alkoxy, hydroxy, nitro and amino.

2. A compound having, the following formula:

ALB,

NH, in which R is alkyl of from 1 to 8 carbon atoms. 3. A compound having the following formula:

HNoHi in which R is alkyl of from 1 to 8 carbon atoms. 4. A'compound having the following formula:

N C CH:

in which R; is alkyl or from 1 to 8 carbon atoms.

No references cited. 

1. A CHEMICAL COMPOUND OF THE CLASS CONSISTING OF A FREE BASE AND ITS NONTOXIC, PHARMACEUTICALLY ACCEPTABLE ACID ADDITION SALTS, THE FREE BASE HAVING THE FORMULA: 